An injection device with an immobilization mechanism

Abstract

The invention relates to an injection device for injecting doses of a liquid drug, which comprises an immobilization mechanism such that the further use of the injection device is immobilized in response to the needle cannula (20) being exposed to an axial force above a predetermined value: the immobilization mechanism comprises a flexible arm (50) which apply a radial force onto the needle cannula at least during injection.

1 . An injection device for injecting doses of a liquid drug, comprising:
 a housing structure holding a container containing the liquid drug to be injected,   a needle cannula connected to the housing structure and having a distal end with a distal tip for penetrating the skin (S) of a user and a proximal end for connecting to the container and a lumen there between,   a movable needle shield movable relatively to the housing structure between a first position and a second position;
 the first position being a position in which the needle shield covers at least the distal tip of the needle cannula, 
 the second position being a position in which the needle shield is retracted such that the distal tip of the needle cannula is exposed, 
   and wherein the injection device further comprises an immobilization mechanism which immobilizes the injection device in response to the needle cannula being exposed to an axial force above a predetermined value and which immobilization mechanism comprises a flexible arm which apply a radial force onto the needle cannula.   
     
     
         2 . An injection device according to  claim 1 , wherein the predetermined value is the axial force needed to bend the needle cannula. 
     
     
         3 . An injection device according to  claim 1 , wherein the flexible arm is movable from a first radial position to a second radial position in response to bending of the needle cannula. 
     
     
         4 . An injection device according to  claim 3 , wherein the flexible arm when in the second radial position prevents axial movement of the needle shield. 
     
     
         5 . An injection device according to  claim 3 , wherein the flexible arm is provided with a distally pointing end surface which engages the needle shield when the flexible arm is in the second radial position. 
     
     
         6 . An injection device according to  claim 1 , wherein the flexible arm is connected to a needle hub securing the needle cannula. 
     
     
         7 . An injection device according to  claim 1 , wherein a radial force urges the flexible arm radially against the needle cannula. 
     
     
         8 . An injection device according to  claim 1 , wherein the flexible arm is provided with an outwardly pointing protrusion. 
     
     
         9 . An injection device according to  claim 1 , wherein the needle shield is rotatable relatively to the housing structure from a locked to an unlocked position. 
     
     
         10 . An injection device according to  claim 9 , wherein the protrusion abuts the needle shield when the needle shield is rotated to the unlocked position. 
     
     
         11 . An injection device according to  claim 1 , wherein the needle shield is provided with a raised locking area on an inner surface thereof. 
     
     
         12 . An injection device according to  claim 11 , wherein the abutment of the raised locking area with the protrusion generates the radial force urging the flexible arm radially against the needle cannula. 
     
     
         13 . An injection device according to  claim 11 , wherein the raised locking area is provided with at least one sloped surface. 
     
     
         14 . An injection device according to  claim 1 , wherein the flexible arm has a radial extension abutting the needle cannula.